Eraser device and command input system

An eraser device 4 for inputting an erase-operation of a display image to a touch panel 2, the touch panel 2 includes an input point detection unit 31 for detecting, as input points based on a plurality of detection points arranged on or near to a display screen, detecting points where a touch operation is performed; and an erase-operation determination unit 32 for determining whether or not a user's operation is the erase-operation, according to a degree of density of the input points, wherein the eraser device 4 includes a plurality of touch parts (pillar parts 48) to be detected as the input points when brought into contact with or closer to the touch panel, and the plurality of touch parts (pillar parts 48) are formed at such a degree of density that it is determined by the erase-operation determination unit that the erase-operation is being performed. Accordingly, an improved command input system for easily performing the erase-operation to the touch panel can be provided, inexpensively.